Linux, DVI and KVM Switches

I have installed a IOGear GVS1764 4 port DVI KVM switch. The goal is to share a USB mouse and keyboard and a LCD display between one Dell Inspiron Laptop and 2 Dell towers running RHEL 4.0. Everything on the laptop is working fine. I cannot get video through the KVM on either Redhat box. The mouse and keyboard work fine. I contacted IOGear and was told to use a VGA/DVI adapter and a DVI-I cable to allow the analog signal to pass through the KVM. I've installed the cable and adapter with no luck. When I switch to the Redhat boxes the monitor repeatedly scans between digital and analog but eventually the monitor goes to sleep. If I bypass the KVM and plug the Monitor directly into the tower, video works fine.

Any ideas???

I'm to the point that I am looking into a TV card for the towers but have been unable to locate a card with Linux drivers.

BTW, the one tower is a Dell Dimension 1100, the other is a Dell Poweredge 440SC. The monitor is a Samsung 971p with the generic LINUX display drivers are installed.